Extend upsert() to copy from existing files.

[calebfaruki]

Abstract

Some Google Drive users have special template files that need to be present in newly created directories to minimize time. It's also possible that a developer may need to know the ID of this file in advance so that it can be monitored for changes.

Resources

• Google Rest API Node.js Client Documentation

Changes to make

• _upsertFile() should check for the presence of a templateId and call _duplicateGoogleFile() when appropriate.
• Create a _duplicateGoogleFile() private method to copy an existing file and upsert it into the target folder.